U.S. patent application number 14/091981 was filed with the patent office on 2014-05-29 for battery cell construction.
This patent application is currently assigned to Blue Spark Technologies, Inc.. The applicant listed for this patent is Blue Spark Technologies, Inc.. Invention is credited to Gary R. Tucholski.
Application Number | 20140147723 14/091981 |
Document ID | / |
Family ID | 50773571 |
Filed Date | 2014-05-29 |
United States Patent
Application |
20140147723 |
Kind Code |
A1 |
Tucholski; Gary R. |
May 29, 2014 |
Battery Cell Construction
Abstract
A flexible battery includes at least one electrochemical cell
for generating an electrical current, including a cathode collector
layer, a cathode layer, an anode layer, and an optional anode
collector layer, some or all of which are formed of a dried or
cured ink. A first substrate includes a pair of opposed side
portions. A first electrode contact is provided that is
electrically coupled to the cathode collector layer and is disposed
along one of the pair of opposed side portions of the first
substrate, and a second electrode contact is provided that is
electrically coupled to the anode layer and is disposed along the
other of the pair of opposed side portions of the first substrate.
The cathode collector layer includes a geometry having a height and
a width such that the number of squares is approximately 5 or
less.
Inventors: |
Tucholski; Gary R.; (North
Royalton, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Blue Spark Technologies, Inc. |
Westlake |
OH |
US |
|
|
Assignee: |
Blue Spark Technologies,
Inc.
Westlake
OH
|
Family ID: |
50773571 |
Appl. No.: |
14/091981 |
Filed: |
November 27, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61730083 |
Nov 27, 2012 |
|
|
|
Current U.S.
Class: |
429/124 |
Current CPC
Class: |
H01M 6/40 20130101; H01M
6/46 20130101; H01M 2300/0014 20130101; H01M 6/045 20130101; H01M
4/12 20130101; H01M 2/0215 20130101; H01M 6/06 20130101; H01M 4/08
20130101; H01M 4/70 20130101; H01M 2300/0005 20130101 |
Class at
Publication: |
429/124 |
International
Class: |
H01M 10/04 20060101
H01M010/04 |
Claims
1. A flexible battery including at least one electrochemical cell
for generating an electrical current, the battery including: a
first substrate including a pair of opposed side portions; a second
substrate; a cathode collector layer provided on the first
substrate between the pair of opposed side portions and being
formed of a dried or cured ink; a cathode layer provided on the
cathode collector layer and being formed of a dried or cured ink;
an anode layer provided on the first substrate between the pair of
opposed side portions, wherein the cathode and anode layers are
disposed in a co-planar arrangement; an electrolyte layer including
a liquid electrolyte in contact with both of the cathode layer and
the anode layer, wherein the first substrate is connected and
sealed to the second substrate to form an inner space containing
the electrolyte, and also containing at least a major portion of
the cathode layer and the anode layer within the inner space; and a
first electrode contact that is electrically coupled to the cathode
collector layer and is disposed along one of the pair of opposed
side portions of the first substrate, and a second electrode
contact that is electrically coupled to the anode layer and is
disposed along the other of the pair of opposed side portions of
the first substrate, wherein the cathode collector layer includes a
geometry having a height and a width such that the number of
squares is approximately 5 or less, wherein the number of squares
is determined by dividing the cathode collector layer height
extending in a direction between the pair of opposed side portions
by the cathode collector layer width extending in a direction along
one of the pair of opposed side portions of the first
substrate.
2. The flexible battery of claim 1, wherein the cathode collector
layer includes a geometry having a height and a width such that the
number of squares is approximately 1 or less.
3. The flexible battery of claim 1, further including an anode
collector layer provided between the anode layer and the first
substrate, wherein the cathode collector layer and the anode
collector layer are disposed in a co-planar arrangement.
4. The flexible battery of claim 3, wherein the cathode collector
layer is disposed along one of the pair of opposed side portions of
the first substrate, and the anode collector layer is disposed
along the other of the pair of opposed side portions of the first
substrate.
5. The flexible battery of claim 4, wherein the second electrode
contact that is electrically coupled to the anode collector
layer.
6. The flexible battery of claim 3, wherein at least one of the
anode layer and the anode collector layer is formed of a dried or
cured ink.
7. The flexible battery of claim 6, wherein the anode layer
includes printed zinc.
8. The flexible battery of claim 3, wherein the anode collector
layer includes a geometry having a height and a width such that the
number of squares is approximately 5 or less, wherein the number of
squares is determined by dividing the anode collector layer height
extending in a direction between the pair of opposed side portions
by the anode collector layer width extending in a direction along
one of the pair of opposed side portions of the first
substrate.
9. The flexible battery of claim 1, further including a frame
interposed between the first and second substrates to connect and
seal the first substrate to the second substrate to form the inner
space.
10. The flexible battery of claim 9, wherein the frame includes at
least one of a cured or dried adhesive ink, and a
pressure-sensitive adhesive.
11. The flexible battery of claim 1, wherein one of the first and
second substrates includes a cutout area extending therethrough
such that one of the first and second electrode contacts is exposed
through the cutout area.
12. The flexible battery of claim 1, wherein the electrolyte
includes an aqueous solution of zinc chloride (ZnCl2).
13. The flexible battery of claim 1, wherein the electrolyte
includes an alkaline electrolyte including at least one of sodium
hydroxide (NaOH) or potassium hydroxide (KOH).
14. A flexible battery including at least two electrochemical cells
for generating an electrical current, the battery including: a
first substrate including a pair of opposed side portions; a second
substrate; a first electrochemical cell on the first substrate,
including a first cathode collector layer, a first cathode on the
first cathode collector layer, and a first anode, wherein the first
cathode collector layer is provided on the first substrate between
the pair of opposed side portions; a second electrochemical cell on
the first substrate, including a second cathode collector layer, a
second cathode on the second cathode collector layer, and a second
anode, wherein the second cathode collector layer is provided on
the first substrate between the pair of opposed side portions;
first and second liquid electrolytes provided, respectively, in
contact with the first and second electrochemical cells, wherein
the second substrate layer is connected to the first substrate
layer to form first and second inner spaces, respectively,
containing each of said first and second liquid electrolytes; a
first electrical bridge that electrically couples the first
electrochemical cell to the second electrochemical cell in a
parallel arrangement; and a first electrode contact that is
electrically coupled to the first cathode collector layer and is
disposed along one of the pair of opposed side portions of the
first substrate, and a second electrode contact that is
electrically coupled to the first anode layer and is disposed along
the other of the pair of opposed side portions of the first
substrate, wherein each of the first and second cathode collector
layers includes a geometry having a height and a width such that
the number of squares is approximately 5 or less, respectively,
wherein the number of squares is determined by dividing the
respective cathode collector layer height extending in a direction
between the pair of opposed side portions by the respective cathode
collector layer width extending in a direction along one of the
pair of opposed side portions of the first substrate.
15. The flexible battery of claim 14, further including first anode
collector layer provided to the first electrochemical cell between
the first anode layer and the first substrate, and a second anode
collector layer provided to the second electrochemical cell between
the second anode layer and the first substrate.
16. The flexible battery of claim 15, wherein the electrical bridge
electrically couples the first and second cathode collector layers
together, and wherein the battery further includes a second
electrical bridge that electrically couples the first and second
anode collector layers together.
17. The flexible battery of claim 16, wherein the first electrode
contact is provided on the first electrical bridge, and the second
electrode contact is provided on the second electrical bridge.
18. The flexible battery of claim 15, wherein each of the first and
second anode collector layers includes a geometry having a height
and a width such that the number of squares is approximately 5 or
less, respectively, wherein the number of squares is determined by
dividing the respective anode collector layer height extending in a
direction between the pair of opposed side portions by the
respective anode collector layer width extending in a direction
along one of the pair of opposed side portions of the first
substrate.
19. The flexible battery of claim 14, wherein both of the first and
second cathode collector layers are disposed along the same one of
the pair of opposed side portions of the first substrate, and
wherein both of the first and second anodes are disposed along the
same other of the pair of opposed side portions of the first
substrate.
20. The flexible battery of claim 14, wherein the first cathode and
anode layers are disposed in a co-planar arrangement, and wherein
the second cathode and anode layers are disposed in a co-planar
arrangement.
21. The flexible battery of claim 14, wherein all of said first and
second cathode current collectors, first and second cathodes, and
first and second anodes include cured or dried inks.
22. The flexible battery of claim 14, further including third and
fourth electrochemical cells on the first substrate that each
include a cathode collector layer that is electrically coupled to
the first and second cathode collector layers.
23. The flexible battery of claim 14, wherein the electrolyte
includes an aqueous solution of zinc chloride (ZnCl2).
24. The flexible battery of claim 14, wherein the electrolyte
includes an alkaline electrolyte including at least one of sodium
hydroxide (NaOH) or potassium hydroxide (KOH).
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
application Ser. No. 61/730,083, filed on Nov. 27, 2012, which is
incorporated herein in its entirety by reference thereto.
FIELD OF THE INVENTION
[0002] The present invention relates generally to an
electrochemical cell or battery, and more specifically to a high
current thin electrochemical cell and method of manufacturing said
electrochemical cell.
BACKGROUND OF THE INVENTION
[0003] In the past 100 years or so, electrical or electronic
circuits, have seen a dramatic change in their design and their
assembly process. About 100 years ago, DC powered circuits were
hard wired and hand soldered in a box format. The high current
electronic or electrical components were fastened to the box and
then they were manually connected by hand soldering wire of
sufficient diameter to carry the required currents and voltages. In
many of these circuits the large sized, multi voltage batteries
were placed in a battery compartment and then they were also hand
soldered into the circuit. Typical battery sizes could be a 6 volt
lantern battery or a battery pack made of multiple 6'' size unit
cells or even possibly some smaller sizes. When the batteries were
depleted, they were desoldered and replaced in the same manner as
when the circuit was made.
[0004] About 60 years ago with the invention of the transistor and
other electronic parts, the design and manufacturing of circuits
changed drastically. Due to the electronic changes, which required
much lower currents and many times lower voltages, circuits could
be made in a more efficient and compact manner. This allowed
circuits to be made on a circuit board in a wave soldering method.
As part of this wave soldering assembly method, battery holders
were also included into the circuit. Due to the big reduction in
required voltages and currents the power source size could also be
reduced in size. Typical power sizes could now be D, C, AA, AAA,
transistor 9 volt battery or even coin or button cells. In these
new circuits with the battery holder, the consumer could install
the battery when he begins using the device as well making it very
easy to replace the depleted batteries.
[0005] In recent years, as described in several Blue Spark patent
applications, printed electronics on flexible substrates has become
a new process and is growing in popularity. In this process, some
or all of the circuit is printed as well as some of the electronic
components. Typically this type of circuit could include a display,
IC chip, sensor, antennae, lights and a relatively low capacity
power source such as a flat printed battery. In some applications,
the power source could also be printed in a totally integrated
manner.
[0006] Alternatively, the power source can be integrated in a
different manner. In order to reduce costs, the power source can be
a printed or otherwise constructed as a flat battery that is
provided as a complete cell or battery for later integration into
the desired circuit. A typical cell can provide, for example, about
1.5 volts DC. Where greater voltages are required, it is
conventionally known to connect two or more cells in series to
increase the voltage. Similarly, multiple cells can be connected
together in parallel to increase the effective capacity. For
example, a battery can include two cells electrically connected in
series to provide 3 volts DC. Still, it is desirable to reduce the
overall size of the battery, even with multiple cells, for use in
small circuits. Various designs and methods of manufacture of a
flat cell and batteries are described in co-pending U.S.
application Ser. No. 11/110,202 filed on Apr. 20, 2005, Ser. No.
11/379,816 filed on Apr. 24, 2006, Ser. No. 12/809,844 filed on
Jun. 21, 2010, Ser. No. 13/075,620 filed on Mar. 30, 2011, Ser. No.
13/625,366 filed on Sep. 24, 2012, and Ser. No. 13/899,291 filed on
May 21, 2013, as well as issued U.S. Pat. Nos. 8,029,927,
8,268,475, 8,441,411, 8,574,745 all of which are incorporated
herein by reference.
[0007] With the growing market needs for low cost, low capacity
thin flat cells, it would be beneficial to produce a thin, flat,
printable flexible cell that is versatile and inexpensive to
mass-produce. Printable, disposable thin cells that are well suited
for low-power and high-production volume applications would be
useful, especially if they offer adequate voltage, sufficient
capacity, rate capability, and low-cost solutions. Conventional
low-profile batteries typically have few of these attributes, if
any.
[0008] Furthermore, in recent years there has been a growing need
for various electronic devices, such as active RFID tags, sensors
with RFID tags, skin patches with sensors to detect body
temperature, as well as electronics to log and wirelessly transmit
and/or receive such data, skin patches that deliver iontophoretic
or other electrical functionality, etc. These various electronic
devices can have various electrical loading characteristics. Thus,
it can be beneficial to provide thin flat power sources that can
reliably deliver relatively higher currents. In one example, the
thin flat power sources can be separately manufactured and later
electrically coupled to various electronic devices. In another
example, the manufacture of the thin flat power sources can be
integrated with the manufacture of the desired circuitry of
electrical components to power the components.
BRIEF SUMMARY OF THE INVENTION
[0009] The following presents a simplified summary of the invention
in order to provide a basic understanding of some example aspects
of the invention. This summary is not an extensive overview of the
invention. Moreover, this summary is not intended to identify
critical elements of the invention nor delineate the scope of the
invention. The sole purpose of the summary is to present some
concepts of the invention in simplified form as a prelude to the
more detailed description that is presented later.
[0010] In accordance with one aspect of the present invention, a
flexible battery includes at least one electrochemical cell for
generating an electrical current, the battery including a first
substrate including a pair of opposed side portions and a second
substrate. A cathode collector layer is provided on the first
substrate between the pair of opposed side portions and being
formed of a dried or cured ink, and a cathode layer provided on the
cathode collector layer and is formed of a dried or cured ink. An
anode layer is provided on the first substrate between the pair of
opposed side portions, wherein the cathode and anode layers are
disposed in a co-planar arrangement. An electrolyte layer includes
a liquid electrolyte in contact with both of the cathode layer and
the anode layer, wherein the first substrate is connected and
sealed to the second substrate to form an inner space containing
the electrolyte, and also containing at least a major portion of
the cathode layer and the anode layer within the inner space. A
first electrode contact is provided that is electrically coupled to
the cathode collector layer and is disposed along one of the pair
of opposed side portions of the first substrate, and a second
electrode contact is provided that is electrically coupled to the
anode layer and is disposed along the other of the pair of opposed
side portions of the first substrate. The cathode collector layer
includes a geometry having a height and a width such that the
number of squares is approximately 5 or less. The number of squares
is determined by dividing the cathode collector layer height
extending in a direction between the pair of opposed side portions
by the cathode collector layer width extending in a direction along
one of the pair of opposed side portions of the first
substrate.
[0011] In accordance with another aspect of the present invention,
a flexible battery includes at least two electrochemical cells for
generating an electrical current, the battery including a first
substrate including a pair of opposed side portions and a second
substrate. A first electrochemical cell is provided on the first
substrate, including a first cathode collector layer, a first
cathode on the first cathode collector layer, and a first anode,
wherein the first cathode collector layer is provided on the first
substrate between the pair of opposed side portions. A second
electrochemical cell is provided on the first substrate, including
a second cathode collector layer, a second cathode on the second
cathode collector layer, and a second anode, wherein the second
cathode collector layer is provided on the first substrate between
the pair of opposed side portions. First and second liquid
electrolytes are provided, respectively, in contact with the first
and second electrochemical cells, wherein the second substrate
layer is connected to the first substrate layer to form first and
second inner spaces, respectively, containing each of said first
and second liquid electrolytes. A first electrical bridge is
provided that electrically couples the first electrochemical cell
to the second electrochemical cell in a parallel arrangement. A
first electrode contact is provided that is electrically coupled to
the first cathode collector layer and is disposed along one of the
pair of opposed side portions of the first substrate, and a second
electrode contact that is electrically coupled to the first anode
layer and is disposed along the other of the pair of opposed side
portions of the first substrate. Each of the first and second
cathode collector layers includes a geometry having a height and a
width such that the number of squares is approximately 5 or less,
respectively. The number of squares is determined by dividing the
respective cathode collector layer height extending in a direction
between the pair of opposed side portions by the respective cathode
collector layer width extending in a direction along one of the
pair of opposed side portions of the first substrate.
[0012] It is to be understood that both the foregoing general
description and the following detailed description present example
and explanatory embodiments of the invention, and are intended to
provide an overview or framework for understanding the nature and
character of the invention as it is claimed. The accompanying
drawings are included to provide a further understanding of the
invention and are incorporated into and constitute a part of this
specification. The drawings illustrate various example embodiments
of the invention, and together with the description, serve to
explain the principles and operations of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing and other aspects of the present invention
will become apparent to those skilled in the art to which the
present invention relates upon reading the following description
with reference to the accompanying drawings, in which:
[0014] FIG. 1 shows one example prior art battery construction;
[0015] FIG. 2 shows another example prior art battery
construction;
[0016] FIG. 3 shows a chart illustrating experimental results using
the batteries of FIGS. 1-2 in a first experimental regime;
[0017] FIG. 4 shows a chart illustrating experimental results using
the battery of FIGS. 1-2 in a second experimental regime;
[0018] FIG. 5 shows one new example battery construction according
to an aspect of the instant application;
[0019] FIG. 6 shows another new example battery construction
according to another aspect of the instant application;
[0020] FIG. 7 shows a chart illustrating experimental results using
the battery of FIGS. 1-2 and 4-5 in a third experimental regime;
and
[0021] FIG. 8 shows a chart illustrating experimental results using
the battery of FIGS. 1-2 and 4-5 in a fourth experimental
regime.
DESCRIPTION OF EXAMPLE EMBODIMENTS
[0022] Example embodiments that incorporate one or more aspects of
the present invention are described and illustrated in the
drawings. These illustrated examples are not intended to be a
limitation on the present invention. For example, one or more
aspects of the present invention can be utilized in other
embodiments and even other types of devices. Moreover, certain
terminology is used herein for convenience only and is not to be
taken as a limitation on the present invention. Still further, in
the drawings, the same reference numerals are employed for
designating the same elements.
[0023] Generally, this application relates to a high current thin
electrochemical cell and methods of manufacturing said
electrochemical cell. Although the concepts herein are expressed
with an example battery using a co-planar construction, they could
also be used with co-facial cell designs in various geometries.
[0024] For the past 100 years or so, dry cells have been made with
various types of chemical systems that include Alkaline Zn/MnO2,
C/Zn with various electrolytes, Li/MnO2 and others. Also, for the
most part these cells have been in various geometrical shapes that
include cylindrical, prismatic, and thin flat structures. In these
conventional constructions, the cells as well as the electrodes
were tall and narrow. When greater capacity and/or greater rate
capability was required, cell designers just made these packages
larger. If less capacity was required, the cells were just made
smaller. Since this design criteria was successful, when printed
thin flat cell were introduced about 15-20 years ago, the same
design criteria was used with some success. Recently, the challenge
of designing smaller cells with high drain capabilities, different
design criteria was needed. This new criteria is explained in the
following paragraphs.
[0025] In making printed thin flat cells with a printed anode,
Applicant has learned that conventional "tall and narrow cells and
electrodes" (i.e., see FIGS. 1-2) could be changed, if cell
performance for drain rates and discharge efficiencies were to be
functional and efficient at different drain rates. Thin printed
cells, for the most part, use inks for the electrode collectors and
electrodes and these inks are usually less conductive than metallic
parts found in the other constructions and in Applicant's early
cells, which had a zinc foil anode. When tall and narrow cells with
tall and narrow electrodes are made, the cells internal resistance
could be high, thus it becomes a potential barrier for high
currents and high discharge efficiencies. The cell's internal
resistance is due to many items, such as: (A) electrolyte
conductivity; (B) separator resistance; (C) resistance of both
electrodes; and (D) resistance of both electrode collectors.
[0026] Generally, the first two items (A and B) are relatively
smaller factors, while the last two items (C and D) including the
resistance of the both electrodes and the resistance of both
collectors are relatively larger factors contributing to the cell's
overall resistance. The electrodes and collectors conductivity are
normally lower than with metallic parts since these inks are
conductive powders mixed with non-conductive binders and other
materials. Applicant has now discovered that an even bigger factor
related to high currents and high discharge efficiencies may be the
geometry of the electrodes and their collectors.
[0027] FIGS. 1-2 illustrate conventional battery constructions to
describe this reason and their effect of high resistances, and how
they could be easily reduced. FIG. 1 shows a top view of one
example of Applicant's convention cell 1000. Various designs and
methods for manufacturing of a flat cell and batteries are
described in Applicant's co-pending U.S. application Ser. No.
11/110,202 filed on Apr. 20, 2005, Ser. No. 11/379,816 filed on
Apr. 24, 2006, Ser. No. 12/809,844 filed on Jun. 21, 2010, Ser. No.
13/075,620 filed on Mar. 30, 2011, Ser. No. 13/625,366 filed on
Sep. 24, 2012, and Ser. No. 13/899,291 filed on May 21, 2013, as
well as issued U.S. Pat. Nos. 8,029,927, 8,268,475, 8,441,411,
8,574,745, all of which are incorporated herein by reference.
[0028] Conventional cell 1000 features a bottom, first substrate
101, which is the base of the construction and can be a five ply
laminated structure. For clarity of this description, the top cover
is not shown (although it can be similar to the bottom
layer/cover). On the topside of substrate 101, a carbon cathode
collector layer 2 is printed on part of the substrate 101. This
cathode collector layer 2 extends from the inside of the bottom
seal 1A to the top of the cell 1000 and forming the positive
contact 4. Just before the contact area 4, the cathode collector
layer 2 passes under the top seal 1C. After the cathode collector
layer 2 is thoroughly dried, a cathode 3 is printed over the
collector area that is inside of the seal area, which is formed by
the inside edges of the four seal edges 1A, 1B, 1C, and 1D. These
two items cathode collector layer 2 and cathode 3 form the
cathode-cathode assembly 23. Adjacent to cathode-collector assembly
23, is the anode assembly 57 is laminated to the substrate 101.
Applicant's conventional cells used a zinc foil anode strip 7,
which was laminated to a double-sided pressure adhesive 5. The
present manufacturing process dictates that the anode--collector
assembly layer extends from the bottom of the cell to the top of
the cell 1000 beyond the top seal 1C forming the negative contact
6. After this anode subassembly 57 was made, the bottom release
liner was removed and the anode subassembly 57 was laminated to the
cells substrate 101 just adjacent (approximately 0.060'' gap 10) to
the cathode-collector assembly 23. After the electrodes are in
place, a separator 8 is placed over the anode assembly 57 and
cathode assembly 23 and inside of the seal area. The separator is
typically smaller than the inside of the seal area. Then an
electrolyte 17 such as a 27% aqueous solution of ZnCl2 is added to
cell 1000 separator 8. In the case of this example cell, the
cathode-collector assembly was approximately 2.80'' tall and
approximately 0.95'' wide, and the anode for this cell was
approximately 0.20'' wide and approximately 2.80'' tall (this does
not include the area in the bottom seal area 1A).
[0029] FIG. 2 shows an alternate cell construction with a printed
anode assembly 999, instead of the zinc foil anode strip described
above. Cell 1100 of FIG. 2 uses a printed zinc anode 99, which is
printed over anode collector 9, and the anode width is increased to
approximately 0.270'' wide. All of the items are the same or
similar to those in FIG. 1, except for the printed anode assembly
999 with the printed carbon anode collector 9 and printed anode 99.
Both of the anode collector 9 and cathode collector 2 can be
printed at the same time (or even at different times), and can use
the same inks as used for the cathode collector 2 of cell 1000.
[0030] Surface resistivity, which is also known as "sheet
resistance," is expressed in ohms per square. The sheet resistance
is a measurement of resistance of thin films that have a generally
uniform thickness. Sheet resistance is applicable to
two-dimensional systems where the thin film is considered to be a
two dimensional entity. It is analogous to resistivity as used in
three-dimensional systems. When the term sheet resistance is used,
the current must be flowing along the plane of the sheet, and not
perpendicular to it.
[0031] The conductive height is the distance that current has to
travel between regions (top to bottom) of the cathode collector and
of the anode collector to the respective electrode contact. By
essentially decreasing the conductive height, lower cell internal
resistance results. In addition, the currents can be higher because
the resistance of the cathode collector is relatively lower. The
resistance is lower because the number of squares is reduced. The
resistance of the cathode collector from its bottom to its top,
including the positive contact, can be determined by calculating
the number of squares in the cathode collector. The number of
squares is determined by dividing the collector height, by the
narrowest width of the collector area. The number of squares using
the new cell designs herein is greatly reduced as compared to that
of a similarly sized cell using the standard construction. For
example, the number of squares of the instant application can be
generally equal to three or less. In another example, the number of
squares of the instant application can be generally equal to one or
less.
[0032] Conductive inks are normally characterized in the industry
by their conductivity in terms of ohms/square at one mil of dry
thickness. The resistance of these two electrodes in this example
cell size (i.e., FIGS. 1-2) can be calculated in the following
manner. Each electrode collector assembly is approximately 2.80''
tall (7.1 cm) with the cathode collector 2 being approximately
0.95'' wide (2.43 cm), and the zinc foil anode is also
approximately 2.80'' tall (7.1 cm) and approximately 0.20'' (0.51
cm) wide. In cell 1000 of FIG. 1, the cathode collector has
approximately 2.9 squares and the anode collector has approximately
14.0 squares. The resistivity of the carbon ink collector which has
a dry thickness of approximately 0.001'' is approximately 33 ohms
per Square (as measured by Applicant). This means that the
theoretical resistance of the cathode collector is approximately 96
ohms (33 ohms/square.times.2.9 squares). The anode has a very
highly conductive zinc foil with a resistivity of approximately
5.5.times.10.sup.-4 ohms/cm (handbook value). The calculation for
the anode resistance is as follows: Anode
resistance=(height/surface area of the entire
collector).times.Resistivity. Using the above example values, the
example calculation is as follows: (7.1
cm/(7.1.times.0.51)).times.5.5.times.10.sup.-4=approximately
0.00108 ohms (theoretical).
[0033] Due to many factors such as zinc purity, surface
contamination, measuring techniques, and instrument contact
resistance, the anode resistance was actually measured by Applicant
to be approximately 1-2 ohms, using a Fluke brand multi-meter. Now
when the cell has a printed zinc ink, its resistance is usually
greater than the anode with the zinc foil. Typical resistances for
anodes as described in FIG. 2 are calculated as follows: 2.8''
tall/0.27'' wide (wider than zinc foil) or approximately 10.4
squares. The printed zinc ink resistivity is approximately 225
ohms/square at 1 mil thickness (as measured by Applicant);
therefore, the anode resistance is calculated as follows: 10.4
squares.times.approximately 225 ohms/square @ 1 mil thick/6 mils
thick=approximately 390 ohms. It is noted that the resistivity of
225 ohms/square occurs at 1 mil thickness of the material, and that
the resistivity decreases with a thicker material. Printed anodes
are typically thicker than foil anodes due to the porosity of the
print, because of printing process, the binder and the carbon used
in the formula. Here, the anode was approximately 6 mils thick,
which is reflected in the above calculation by reducing the
resistance by a corresponding factor of 6.
[0034] Turning now to FIGS. 3-4, a comparison of the cell
performance of FIGS. 1-2 is illustrated. The cell performance in
FIG. 3 (the average cell closed circuit voltage (CCV) at
approximately 2 sec pulse voltage at various loads) and FIG. 4
(continuous discharge at a load of 470 ohms) or about an average
current of about 2 mA, which is a very high drain rate for this
small cell) is illustrated between cell 1000 in FIG. 1 with zinc
foil and cell 1100 in FIG. 2 with printed zinc. The experimental
data was tabulated from experiments done at room temperature. FIG.
4 also shows discharge efficiencies for the two compared cells
1000, 1100. FIG. 3 shows cells 1000 (zinc foil anode) of FIG. 1 on
the high drain rates have a much higher pulse voltages and currents
than the cells 1100 (printed zinc) of FIG. 2; however as the load
is decreased to about 2100 ohms or about 0.7 mA, there is no
difference between the two, thus showing that the cell electrode
resistance is not a large factor for lower currents. FIG. 4 shows
the cells 1000 of FIG. 1 made with a zinc foil anode assembly 57
have a much higher operating voltage for the entire test as well as
twice the operating time to 0.90 volts, twice the output capacity
and twice the discharge efficiency than the cells of the cells 1100
of FIG. 2 with a printed zinc anode. Both of these cell
constructions have an active area of approximately 2.66 sq. inches.
Since printed zinc has many advantages over a zinc foil anode, it
would be advantageous to make these cells capable of higher drain
rates and high discharge efficiencies. These advantages include
lower cost, easier to process, more design freedom that would allow
many more shapes and sizes. Based on the above, it appears that
lower electrode and collector resistances would help this
situation.
[0035] Applicant has now discovered that an even bigger factor
related to relatively higher currents and higher discharge
efficiencies may be the geometry of the electrodes and their
collectors. Applicant has further discovered that minimizing the
number of squares in a cell appears to be a beneficial and
relatively easy-to-implement method to accomplish this goal. The
following is verification of this concept. By using a new design
criteria described herein of electrodes being short and wide,
instead of tall and narrow, the electrode-collector resistances are
greatly reduced; therefore this design will produce relatively
higher drain rates and higher discharge efficiencies as compared to
the conventional cells. It is understood that although the new
cells are described herein as "short and wide," this description is
done for convenience with respect to the illustrated embodiments,
and is not intended to be a limitation upon the instant
application. The new cell design could utilize various geometries
as desired, including circular, oval, square, and polygonal,
etc.
[0036] The batteries described herein are illustrated using a
co-planar construction. A co-planar construction provides several
advantages, in that they are relatively easier to manufacture,
provide consistent, reliable performance, and provide external
contacts that are on the same plane. Initially thin printed cells
were designed primarily as a power sources that supply relatively
low levels of current, now there is an increasing need for a thin
flat power sources that can reliably deliver currents higher than
those provided by the standard co-planar electrochemical cell
construction. Due to the need for thin flat power sources that can
reliably deliver higher currents, constructions were sought that
had the same advantages as the earlier co-planar cells/batteries,
but could also deliver higher currents. As shown in FIGS. 5-6, a
top view of example new short-and-wide battery construction is
illustrated that is capable of delivering higher currents, as well
as other significant performance advantages. These generally
include one or more of the following; such as lower cathode
collector resistance; lower cell internal resistance which results
in higher pulse voltages on the same load; a pulse voltage
improvement that is larger as the current becomes higher; an
increased operating time to high voltage cutoffs on higher drain
tests and/or higher discharge efficiencies. The new designed
electrochemical cell was also designed to be easily made by
printing (e.g., through use of a printing press), and allows, for
example, for the cell/battery to be directly integrated with an
electronic application.
[0037] Turning now to FIG. 5, a top view illustrates one example
new cell design 2000. For clarity the top cover is not shown
(although it can be similar to the bottom layer/cover). Cell 2000
features substrate 201, which is the same or similar substrate as
used in cells 1000 and 1100, as the base of the construction. On
top of substrate 201 a carbon cathode collector layer 20 is printed
on part of the substrate 201. This collector is approximately 1.0''
wide and extends from near the middle of the cell that leaves a gap
10 that is about 0.060'' from the anode collector 30. This cathode
collector layer 20 also extends under the top seal 2C to form the
positive contact 4, which is located along side 201A. It is
contemplated that the cathode collector layer 20 could also extend
under either or both of the side seals 2B, 2D to provide a slightly
wider layer that could further reduce electrical resistance. After
the collector is thoroughly dried, a cathode 21 is printed over the
collector area that is inside of the seal area 400, which is
approximately 0.825 sq. inches and is about 0.050'' away from the
inside edges of the three seal edges 2B, 2C, and 2D (although other
dimensions are contemplated). These two items 20 and 21 form the
cathode-cathode collector assembly 25. Similarly, the anode
collector 30 and anode 31 form the anode-anode collector assembly
35. The anode collector layer 30 is about 0.60'' tall and extends
from the outside of the bottom seal 2A to form the negative contact
6, which is located along side 201B to the electrode gap near the
center of the cell. It is also contemplated that the anode
collector layer 30 could also extend under either or both of the
side seals 2B, 2D to provide a slightly wider layer that could
further reduce electrical resistance. Adjacent to cathode-collector
assembly 25, with a gap 10 of approximately 0.060'' therebetween,
the anode-anode collector assembly 35 is printed on the substrate
201. In this cell 2000, the cathode is about 0.70'' tall, while the
cathode-collector assembly is approximately 1.0'' tall and extends
to the top of the cell to form positive contact 4. The anode for
this cell is approximately 1.00'' wide, approximately 0.30'' tall
and about 0.050'' away from seals 2A, 2B, and 2D. In this
particular example, the reason for this 30:70 ratio for the
anode/cathode height is to allow for a cell balance to have about
two to three times more anode than cathode in terms of mAHrs.
However, it is understood that the anode-to-cathode ratio could be
different, depending on many factors including cell size, shape,
and printing method and may be adjusted to achieve a desired
performance profile for the completed cell. For example, and not by
limitation, other possible anode-to-cathode ratios could include
20:80, 25:75, 35:65, 40:60, 60:40, 65:35, 70:30 etc.
[0038] Because Applicant has discovered that relatively higher
currents and higher discharge efficiencies of the batteries may be
achieved by minimizing the number of squares in a cell, preferably
the cathode collector layer 20 of the battery includes a geometry
having a height and a width such that the number of squares is
approximately 5 or less. More preferably, the cathode collector
layer includes a geometry having a height and a width such that the
number of squares is approximately 5 or less, or more preferably 3
or less, or even more preferably 1 or less. In one example, as
shown in FIG. 5, the number of squares is determined by dividing
the cathode collector layer height (CCH), extending in a direction
between the pair of opposed side portions (e.g., between sides 201A
and 201B), by the cathode collector layer width (CCW) extending in
a direction along one of the pair of opposed side portions (e.g.,
side 201A) of the first substrate 201. In this shown example having
a rectangular geometry, the height and width (CCH and CCW) of the
cathode collector layer are measured along substantially
perpendicular axes. Thus, it can be seen that the conductive
distance CCH that current has to travel along the cathode collector
layer 20 to the respective positive electrode contact 4 has been
substantially reduced as compared to the conductive distance of
cells 1000 and 1100. Similarly, it is preferable that the anode
collector layer 30 includes a geometry having a height and a width
such that the number of squares is approximately 5 or less, more
preferably 3 or less, and even more preferably 1 or less. The
number of squares is determined by dividing the anode collector
layer height (ACH), extending in a direction between the pair of
opposed side portions (e.g., between sides 201A and 201B), by the
anode collector layer width (ACW) extending in a direction along
one of the pair of opposed side portions (e.g., side 201A) of the
first substrate 201. As before, the ACH and ACW are measured along
substantially perpendicular axes, and as above the conductive
distance ACH that current has to travel along the anode collector
layer 30 to the respective negative electrode contact 6 has also
been substantially reduced as compared to cells 1000 and 1100. As
can be seen in FIG. 5, this construction gives the battery a
short-and-wide configuration. By essentially decreasing the
conductive height, lower cell internal resistance results so that
the currents can be higher because the resistance of the cathode
and anode collector layers are relatively lower.
[0039] In this example, the capacity of the cathode has an input of
about 5.5 mAHrs and the anode has an input about 15 mAHrs (i.e.,
these are theoretical capacities). The resistance of these two
electrodes collector assemblies in this cell size can be calculated
in the similar manner, as was done earlier for cells 1100 and 1000.
The cathode electrode-collector assembly is approximately 1.00''
wide (CCW) and approximately 1.00'' high (CCH) (including area
under the seal 2C), providing about 1.00 Squares (1.0/1.0=1.0). The
resistivity of the carbon ink for the cathode collector is
approximately 33 ohms/square per 0.001'' of thickness (as measured
by Applicant). This means the calculated resistance of the cathode
collector layer is approximately 33 ohms (33 ohms/square.times.1.0
squares), which is only about 34% as was in cell 1100 (which was
calculated to be 96 ohms, see above). For the anode, the anode
electrode-collector assembly is approximately 1.00'' wide (ACW) and
approximately 0.60'' high (ACH) (including area under the seal 2A),
providing about 0.60 Squares (0.60/1.0=0.60). The carbon-zinc ink
resistivity is approximately 225 ohms/square at 1 mil thickness;
therefore, the calculated anode resistance is approximately 22.5
ohms (0.60 squares.times.approximately 225 ohms/square @ 1 mil
thick/6 mils thick). This represents only 6% of the value for cell
1100 of FIG. 2. Again, the anode was approximately 6 mils thick,
which is reflected in the above calculation by reducing the
resistance by a factor of 6.
[0040] In an effort to further increase capacity, FIG. 6 shows
another cell/battery construction 3000. Similar reference numbers
are used from FIG. 5 for similar items. This battery is made by
connecting two cells (e.g., two of cells 2000 of FIG. 5) in
parallel which are separated by the center seal 2E forming a
battery with approximately 11 mAHrs of input capacity. For example,
a first electrochemical cell 40 is provided on the first substrate
201, including a first cathode collector layer, a first cathode on
the first cathode collector layer, and a first anode. The first
cathode collector layer is provided on the first substrate between
the pair of opposed side portions 201A, 201B. Additionally, a
second electrochemical cell 42 is also provided on the first
substrate, including a second cathode collector layer, a second
cathode on the second cathode collector layer, and a second anode.
The second cathode collector layer is provided on the first
substrate between the pair of opposed side portions 201A, 201B.
Both of the first and second cathode collector layers can be
disposed along the same one of the pair of opposed side portions
(e.g., 201A) of the first substrate 201, and both of the first and
second anodes can be disposed along the same other of the pair of
opposed side portions (e.g., 201B) of the first substrate 201.
Additionally, either or both of the first and second
electrochemical cells 40, 42 can include an anode collector layer
between the first/second anode layer and the first substrate.
Preferably, the first and second electrochemical cells 40, 42 are
co-planar. More preferably, the first cathode and anode layers are
disposed in a co-planar arrangement, and the second cathode and
anode layers are disposed in a co-planar arrangement.
[0041] First and second liquid electrolytes are provided,
respectively, in contact with the first and second electrochemical
cells. The battery is completed with the second substrate layer
being connected to the first substrate layer to form first and
second inner spaces, respectively, containing each of said first
and second liquid electrolytes. The first and second inner spaces
are independently sealed. The electrode resistances remains the
same as in cell 2000 and the active area and input is doubled to
approximately 1.75 sq. inches and approximately 11 mAHrs,
respectively.
[0042] Additionally, a first electrical bridge electrically couples
the first electrochemical cell to the second electrochemical cell
in a parallel arrangement. In one example, a printed or laminated
jumper bar 51 can be provided to electrically connect the two
cathode collector layers 20 to provide the parallel construction
and positive contact 4. Additionally, a second electrical bridge 52
electrically couples the first and second anode collector layers
together. Similar constructions using a printed or laminated jumper
bar 52 could be used for the anode collector layers 30 to provide
the parallel construction and negative contact 6. Thus, the first
electrode contact 4 can be provided on the first electrical bridge
51, and the second electrode contact 6 can be provided on the
second electrical bridge 52.
[0043] In order to increase the capacity as well as the discharge
efficiencies on high drains of these cells with short and wide
electrodes, multiple cells could be placed in a parallel
connection, thus two, three, and four which have an input of
approximately 11 to 22 mAHrs. For example, three or more cells
(e.g., three or more of cells 2000 of FIG. 5) could be connected in
parallel to provide additional capacity. In one example, four of
the cells shown in FIG. 5 could be connected in parallel thus
forming a battery that has double the area and input capacity to
approximately 3.5 sq. inches and approximately 22 mAHrs,
respectively. It is further understood that more than four cells
could be connected in parallel to provide even greater
capacities.
[0044] Also the capacities of these multi cell batteries could also
be achieved by making the unit cell larger or possibly only two
cells are in parallel. Alternatively, instead of a multi-cell
battery, a larger single-cell battery could be formed by making the
cathode collector layers 20 printed together as one wide strip
along the top of the battery, with an appropriately sized cathode
layer on top. Similar increased sizing could be provided to a
corresponding anode collector layer and anode. Still, various
geometries are contemplated that maintain a reduced number of
squares for the cathode and anode assemblies. For example, the
cathode and anode assemblies could be enlarged along multiple axes,
so as to provide a geometry that more approaches a square shape
instead of a single long, wide rectangle. Also, this new design
concept is not limited to only coplanar designed cells with a ZnCl2
thin printed construction, but this concept could also be used with
co-facial designs in various geometries, such as flat, cylindrical
and prismatic shapes as well as any electrochemical system.
[0045] Even so, it is understood that a single cell with
approximately 11 mAHrs, or 22 mAHrs of input, or any desired input,
could be designed and made using the short and wide electrode
design approach. For example, a single cell similar to that shown
by cell 2000 of FIG. 5 could be made approximately two times larger
to provide two times the active area for the electrochemical layers
to achieve a two-fold increase in battery capacity, or even four
times larger to provide four times the active area for the
electrochemical layers to achieve a four-fold increase in battery
capacity, or other increase. In one example construction a battery
could provide an electrode area of about 1.75 square inches and 11
mAHrs, or the same as battery 3000 as shown in FIG. 6. This could
be achieved variously, but in one example, a cell of similar
dimensions as cell 3000 could be constructed without the center
seal 2E and could include a single, elongated cathode collector
layer and also a single elongated anode collector layer that
extends the full width of the battery. Similarly, a unit cell with
a capacity of 22 mAHrs capacity (e.g., four times the cell 2000)
could be provided by a battery with an electrode area of about 3.5
square inches by further increasing the dimensions of the cathode
and anode current collector layers along multiple axes. Of course,
the increase in battery size could be achieved by adjusting various
battery dimensions using various geometries. By making larger unit
cells instead of connecting smaller unit cells in parallel, it is
conceivable to produce a more efficient package resulting higher
input capacity for the same package size.
[0046] To verify this construction concept cells/batteries shown in
FIGS. 5-6 and as described in the previous paragraphs were tested,
and the results are summarized in FIGS. 7 and 8 and discussed in
the following paragraphs. The graphs further demonstrate the
performance advantages of thin flexible batteries constructed using
the new short-and-wide design. For clarity, although an example
construction of the four-cell parallel variant is not shown in the
drawings, it will be referred to by reference number 4000 for use
in the experimental results charts of FIGS. 7-8. It is to be
understood that these graphs illustrate only example performances
of the new short-and-wide design, and that the new design cells can
have various other performance characteristics, values, etc. The
experimental data was tabulated from experiments done at room
temperature. FIG. 8 also shows efficiencies for the compared
cells.
[0047] FIG. 7 shows five different curves representing the cells
the cell constructions discussed in the previous paragraphs. For
ease of discussion the cell number discussed in the above
paragraphs will also be used in these discussions. FIG. 7 shows
five different curves each one representing one of the cell
constructions discussed earlier. These curves represent the average
cell closed circuit volts (CCV) under three different two second
long pulses, and the cell current is shown at each data point.
Since high current and high discharge efficiencies were the goal of
the construction changes, these features will be emphasized in the
discussions. These cells of 1000, 1100, 2000, 3000 (e.g., two 2000
cells in parallel), and 4000 (e.g., four 2000 cells in parallel)
have active areas of 2.66, 2.66, 0.85, 1.75, and 3.5 sq. inches
respectively as well as inputs of about 35, 35, 5.5, 11.0 and 22
mAHrs, respectively.
[0048] The new design cells 2000, 3000, and 4000 are compared
electrically with the previous standard designed cells shown in
FIG. 1 (1000) and FIG. 2 (1100). This data shown in FIGS. 7 and 8
confirms the projected improved cell performance. FIG. 7 shows the
two cell constructions performance in terms of two-second pulse
current drain with a range of three different pulse loads. This
data clearly shows that the original construction 1100 featuring
tall and narrow electrodes with a printed zinc anode has much lower
pulse voltages as well much lower currents. The original
construction 1000 with zinc foil has much better results than its
printed zinc version of FIG. 2 cell 1100, but only similar to the
smaller new design cell 3000 that has only approximately 11 mAHrs.
The 22 mAHrs cell 4000 at all of the drain rates ranging from 0.7
mA to .about.2.9 mA has superior performance, than the much larger
cells 1000 with zinc foil and cell 1100 with printed zinc that have
35 mAHrs of capacity.
[0049] When these two different cell designs are discharged
continuously with a 470 ohm load, as shown in FIG. 8, the results
show that the smaller 22 mAHr cells of the new design clearly
outperform the much larger original designed cells with printed
zinc as well the cell with zinc foil (1000). Using a cutoff voltage
of 0.90 volts, the 22 mAHr cell with the new design of short and
wide electrodes produced approximately 5.9 mAHrs of power with a
discharge efficiency of 27% (i.e., cell output/cathode input). The
zinc foil cell (1000), made with the old design and 35 mAHrs of
input, delivered approximately 4.2 mAHrs of capacity and had a
discharge efficiency of only approximately 12%. Comparatively, this
is only 44% as efficient as the new design (4000). Then comparing
the old cell design 1100 with a printed anode and still with
approximately 35 mAhrs of capacity, they delivered only
approximately 2.1 mAHrs which is approximately 6% efficient and is
about only 22% efficient as cell 4000 with the new design. The
performance of the original design cell 1000 with a 35 mAHrs of
input is less efficient than the new design cell/battery 3000 with
only approximately 11 mAHrs of input capacity. This new design cell
3000 gave the same output of approximately 2.1 mAHrs but at an
efficiency of approximately 19%, which is three times higher than
the larger old cell design 1100 with printed zinc.
[0050] In order to construct the new cell designs 2000, 3000, 4000,
the following constructions and methods of manufacture can be
utilized. In one example, the electrochemical cells (i.e.,
batteries) are typically printed and/or laminated on a continuous,
flexible substrate web, and may be formed into a roll or the like.
The individual batteries can be removed from the roll, such as one
at a time. For example, the batteries can be cut from the roll,
and/or perforations of the flexible substrate roll can be provided
for easy tear off. In addition, the batteries can further be
manufactured in an integrated process with one or more electrical
components, such as an antenna, display, and/or a processor, for
example. The multiple facets of this application could be used in
the total package described and/or they could be used individually
or in any combination.
[0051] In one example construction, referring to the batteries of
FIG. 5-6, the cells are printed and assembled on a bottom, first
substrate 201 that includes a pair of opposed side portions 201A,
201B. To provide greater clarity, the batteries are shown without
the top, second substrate. The bottom and/or top substrates can be
a material that includes a plurality of laminated layers. The
plurality of laminated layers can include a structural layer having
an integrated barrier and/or a heat sealing layer, such as any
described herein. The plurality of laminated layers can include any
or all of an inner layer including a polymer film and/or a heat
sealing coating, a high-moisture barrier layer, a first adhesive
layer for connecting said inner layer to said high-moisture barrier
layer, an outer structural layer including an orientated polyester,
and/or a second adhesive layer for connecting said high-moisture
layer to said outer structural layer. The high-moisture barrier
layer can include an oxide coated moisture barrier layer that
non-hermetically seals the battery against moisture, and may or may
not include a metal foil layer. The plurality of laminated layers
could optionally include a metalized layer.
[0052] A current collector layer can be provided separately
underneath each of the cathode and anode of the electrochemical
cell. Each current collector layer can be provided via a dried or
cured ink (e.g., printed), or can be provided via a non-printed
process, such as laminates, adhesives, strips of material, etc.
Indeed, all of the current collectors, anodes, and cathodes can be
provided as cured or dried inks. Generally, the current collector
layer is provided as a different material from the anodes and
cathodes. The anode and cathode of each cell can be printed,
respectively, on each of the cathode collector and/or anode
collectors. It is contemplated that any or all of the current
collectors can be provided directly upon the lower first substrate,
in the same printing station, although any or all of the current
collectors could be provided on top of optional intermediate
layers. Preferably, the cathode collector layer and the anode
collector layer are disposed in a co-planar arrangement.
[0053] The cathode collector layer 20 can be provided on the first
substrate 201 between the pair of opposed side portions 201A, 201B
and can be formed of a dried or cured ink. Similarly, an anode
collector layer 30 can also be provided on the first substrate 201
between the pair of opposed side portions 201A, 201B and can be
formed of a dried or cured ink. The anode collector layer 30 is
provided between the anode layer and the first substrate. In one
embodiment, the cathode collector layer 20 and the anode collector
layer 30 are printed, preferably in the same operation, with the
same carbon ink. In this operation, a gap 10 of about 0.060'' is
maintained between the cathode and anode collectors. In various
examples, the flexible battery can be manufactured (i.e., printed)
directly or indirectly on the bottom, first substrate 201, or can
even be separately manufactured (wholly or partially) and then
attached directly or indirectly to the bottom, first substrate 201.
Next, a sealant can be printed over the collectors in the seal
areas. The sealant could also be printed on the cell perimeters to
form a picture frame pattern.
[0054] The anode 31 is then printed over the anode collector layer
30 that is inside of the seal area, and the cathode 21 is also
printed over the cathode collector layer 20 that is inside of the
seal area. This printing also maintains the gap of about 0.060''
between the cathode and anode. The anode 31 and cathode 21 of each
unit cell can be printed in a co-planar arrangement. The anodes and
cathodes can be comprised of cured or dried inks. In at least one
embodiment, on the large area part of the cathode collector layer
20, the cathode layer 21 is printed using an ink comprising
manganese dioxide, a conductor such as carbon (e.g., graphite) for
example, a binder, and water or other solvent. In various other
examples, the cathodes can be printed using an ink that includes
one or more of manganese dioxide, carbon, NiOOH, silver oxides Ag2O
and/or AgO, HgO, oxygen O2 in the form of an air cell, and Vanadium
oxide VO2. The anode layer 31 can be printed as conductive zinc
ink. In various other examples, the anodes can be printed using an
ink that includes one or more of zinc, nickel, cadmium, metal
hydrides of the AB2 and the AB3 types, iron, and FeS2.
[0055] After all of the printing is completed, then the cell is
assembled. For example, after the electrode layers (anode layer and
cathode layer) are in place, seals 2A, 2B, 2C, and 2D can be placed
around the electrodes. In one example, an optional "picture frame"
can be placed around the electrodes as a spacer. One method is to
print this cell picture frame with a dielectric ink, for example,
such as a cured or dried adhesive ink. Another method is to utilize
a polymer sheet, stamped, die cut, laser cut or similar methods to
form the appropriate "pockets" (inner space or spaces) to house
materials as well as cutouts for the cells contacts. In the
simplified construction being discussed here, the picture frame
could comprise a die cut polymer laminate sheet, such as a
polyester or polyvinyl chloride (PVC), etc., in the middle and
having two outside layers of pressure sensitive adhesive with
release liners (e.g., top surface and bottom surface). Generally,
when stamped frames are used, each "picture frame" has a total
thickness (excluding the thickness of the liners) of about 0.010''
(about 0.003''-0.50''). The "picture frame" can be placed on the
bottom laminate structure after removing a bottom release liner so
that the anode and cathode are centered within the frame.
Alternatively, the picture frame could be replaced by a printed or
laminated adhesive provided in the shape of the above-described
frame. When a printed frame is used, they are generally much
thinner with a thickness of about 0.002'' (e.g., about
0.0005''-0.005''). In some cases, to ensure a leak-free
construction, a sealing and/or caulking adhesive, a heat sensitive
sealant, and/or double sided PSA tape can be placed and/or printed
on top of the anode collector layer and on top of cathode collector
in an area that falls under the picture frame. The sealing adhesive
can also be provided underneath the remainder of the picture frame.
The top PSA layer adheres and seals the top laminate substrate to
the picture frame and bottom PSA layer can be used to adhere and
seal the bottom laminate substrate to the picture frame.
[0056] If an optional picture frame is used, it can be placed over
the printed area and exposes the anode and cathode, as well as the
electrode contacts 4 and 6. The picture frame spacer thickness
controls the cell thickness. For example, this frame can be a three
layer laminate (excluding the two adhesive release liners)
consisting of two layers PSA of about 0.003'' thick on the outside
and a PET layer in the center with a thickness of 0.003'' to about
0.015'' depending on the cell thickness. The picture frame could
feature a cutout to expose the anode and cathode, and also form a
cavity for the electrolyte. Also there can be cutouts on the
opposite sides to expose the negative and positive electrode
contacts to the battery.
[0057] The anodes and cathodes of the electrochemical cell interact
through the electrolyte 17 to create an electrical current. The
electrolyte can include one or more of: zinc chloride, ammonium
chloride, zinc acetate, zinc bromide, zinc Iodide, zinc tartrate,
zinc per-chlorate, potassium hydroxide, and sodium hydroxide. The
liquid electrolyte layer can comprise a polymeric thickener
comprising one or more of polyvinyl alcohol, a starch, a modified
starch, ethyl and hydroxyl-ethyl celluloses, methyl celluloses,
polyethylene oxides, and polyacryamides. Additionally, the
electrolyte layer can further comprise an absorbent paper separator
8. As described herein, the electrolyte is a viscous or gelled
electrolyte. If the electrolyte is not part of the gelled coating,
a cell electrolyte is provided to an absorbent material such as a
"paper separator" 8 that covers or partially covers both
electrodes. The electrolyte can be an aqueous solution of ZnCl2 at
weight percent of about 27% (about 23%-43%) that could also contain
a thickener, such as carboxymethylcellulose (CMC) or other similar
materials at about 0.6% level (about 0.1%-2%). Any of the
electrolytes can include an additive to prevent or reduce gassing
in the electrochemical cell (e.g., prevent or reduce the generation
of hydrogen gas in the cells). The separator 8 is placed in the
spacer cavity over the anode and cathode. The liquid electrolyte 17
is then added to the separator 8, such as a 27% aqueous solution of
ZnCl2 (or other electrolyte solution). After the electrolyte is
added and soaked into the separator, a top substrate (e.g., the
second substrate) is added and heat sealed with the PSA layer on
the top and bottom of the spacer in a picture frame pattern to the
spacer.
[0058] The cell is completed by applying and sealing the top,
second substrate (not shown) to the first, bottom substrate to form
an inner space containing the electrolyte, and also containing at
least a major portion of the cathode layer and the anode layer
within the inner space. The first substrate can be sealed to the
second substrate using the PSA and/or with a heat seal. The top,
second substrate is connected to the bottom, first substrate 201 to
contain the liquid electrolyte 17 such that the electrochemical
cell is sealed. If present, the top, second substrate can be sealed
over the optional picture frame. Prior to applying the top, second
substrate, a release liner, if present (not shown), is removed from
an adhesive layer on top of the optional picture frame. In another
example, a printed adhesive can be used to connect the top and
bottom substrates. Additionally, the printed adhesive may extend
over and cover at least a portion of the anode and/or cathode
layers. In another example, the top and bottom substrates can be
directly connected to each other without an intermediate adhesive
or picture frame. It is also contemplated that where a picture
frame is not utilized, the top laminate substrate is connected to
the bottom laminate substrate to form the inner space containing
the liquid electrolyte.
[0059] When the top, second substrate is sealed over the bottom,
first substrate 201, an outer seal area is formed. The seal area
inhibits, such as prevents, the liquid electrode from leaking out
of each cell. The width of the seal area can vary based on the
overall size and geometry of the battery (and normally the smaller
the cell/battery the narrower the seal width). In one example, the
seal area can have a minimum width of about 0.075 inches. The
maximum width can vary based on the various batteries, with a
typical width of about 0.250'' and can be as large as 0.300 inches,
or even greater. This battery construction with the same geometries
can also be made without the frame in high volumes with a
commercial pouch filling machine. It is contemplated that the seal
area may be substantially the same around the perimeter of each
cell, or may differ along the perimeter of each cell as
desired.
[0060] In order to electrically connect the battery to external
electronics, electrode contacts are provided. For example, a first
electrode 4 contact is electrically coupled to the cathode
collector layer 20 and is disposed along one of the pair of opposed
side portions (e.g., side 201A) of the first substrate 201, and a
second electrode contact 6 that is electrically coupled to the
anode layer 31 and is disposed along the other of the pair of
opposed side portions (e.g., side 201B) of the first substrate 201.
The second electrode contact 6 can be directly electrically coupled
to the anode layer 31, or indirectly electrically coupled via the
anode collector layer (i.e., if the second electrode contact 6 is
electrically coupled to the anode collector layer). The positive
and negative contacts 4, 6 are exposed outside of the
electrochemical cell for connection to other electronics. Either or
both of the positive and negative contacts 4, 6 may have a printed
or laminated conductive layer thereon, such as a printed silver ink
or the like, or may include other layer(s) that facilitate coupling
or electrical conductivity to the electronics. It is further
contemplated that at least one of the first and second substrates
can include a cutout area extending therethrough such that one of
the first and second electrode contacts is exposed through the
cutout area. For example, the top, second substrate could include a
pair of cutouts, with one cutout each located over the desired
location of the positive and negative contacts 4, 6.
[0061] The cell could also be assembled by hand or in an automatic
process with a pouch assembly machine without a spacer. For
example, this can be done by having a roll of printed cells that is
fed through the pouch machine and in the first station, the
separator is cut or blanked out and placed over the anode and
cathode. The next station could pump in the required amount of
electrolyte. A roll of substrate, which is the same or could be
different than the bottom substrate laminate, is matted to the
bottom web. After the two substrates are matted together, the
electrolyte station could be activated. In this situation, the
electrolyte is pumped through very small diameter tubes that are
inserted between the two layers of substrates before they are
sealed together. Next, after the electrolyte is added, the
electrolyte tubes are removed and the cell can be heat sealed in a
picture frame pattern. The assembled cells are then blanked or cut
out of the web.
[0062] Additional constructions and methods of manufacture will be
further discussed. As used herein, unless otherwise explicitly
indicated, all percentages are percentages by weight. Also, as used
herein, when a range such as "5-25" (or "about 5-25") is given,
this means, for at least one embodiment, at least about 5 and,
separately and independently, not more than about 25, and unless
otherwise indicated, ranges are not to be strictly construed, but
are given as acceptable examples. Also herein, a parenthetical
range following a listed or preferred value indicates a broader
range for that value according to additional embodiments of the
application.
[0063] The present application relates to thin, printed
electrochemical cells and/or batteries comprising a plurality of
such cells. Such cells each typically include at least a first
electrode including a first electrochemical layer (e.g., a
cathode), a second electrode including a second electrochemical
layer (e.g., an anode), and an electrolyte that interacts with the
electrodes to create an electrical current. All of the first and
second electrodes and the electrolyte are typically contained
within some structure that provides an external electrical access
to the electrodes for providing an electrical current supply to
some device.
[0064] One method of mass-producing such cells includes depositing
aqueous and/or non-aqueous solvent inks and/or other coatings in a
pattern on a special substrate, such as a laminated polymeric film
layer, for example. The depositing can be by means of, for example,
printing electrochemical inks and/or laminating a metallic foil,
such as zinc foil, for example, on one or more high-speed web
rotary screen printing presses, especially if the desired volumes
are very high. If volumes are relatively lower, say in the
quantities of only about several million or less, then relatively
slower methods such as web printing with flat bed screens could be
appropriate. If the volumes are even lower, such as hundreds or
thousands, then a sheet-fed flat bed printing press may be
utilized, for example. Still, various printing methods can be used
for various desired quantities.
[0065] After the inks are printed and/or the solids have been
properly placed, the cells can be completed (e.g., electrolyte
added, sealed, die cut, stacked and/or perforated and wound into a
roll, or stacked if sheets are used on a printing press). This cell
manufacturing process can also be utilized for integrating one or
more individual cells with an actual electronic application, or
into batteries comprising multiple cells connected in series or
parallel, or some combination of the two. Examples of such devices
and corresponding processes will be described later, but many
additional embodiments are also contemplated.
[0066] As discussed above, the battery may be described as a
printed, flexible, and thin. Such a cell/battery can include, for
example, a lower film substrate that can utilize a special polymer
laminate that has special features, possibly including, for
example, a high moisture barrier layer in the center that is
surrounded by polymer films on both sides. Furthermore, one or both
outside surfaces can be made to be print receptive for printing
information, logos, instructions, identifications, serial numbers,
graphics, or other information or images, as desired.
[0067] Depending on which construction of this battery is used, one
ply of a multi-ply substrate could also feature a heat-sealing
layer that might be co-extruded adjacent the barrier coating. In
addition, a portion one substrate layer of a cell of at least some
embodiments could utilize a cathode current collector and/or an
anode current collector, such as carbon, for example, printed or
coated or otherwise applied on a portion of the film substrate. At
an outside contact area of this collector can also be printed a
layer of a relatively highly conductive ink, such as carbon, gold,
silver, nickel, zinc, or tin, for example, to improve the
conductivity to the application connection, if desired.
[0068] The first and/or second substrates can include various
layers, such as five layers. For example, the various layers of
first substrate can include three plies of film, and two layers of
a UV cured urethane laminating adhesive that can be relatively
thin, such as about 0.2 mils thick, with a range of about 0.1-0.5
mils. In one example, this laminated structure can be supplied by
Curwood Inc., a Bemis Corporation Company of Oshkosh, Wis. The top
film layer can be a heat sealable layer, such as provided by DuPont
(OL series), which is on the inside of the cell and can have an
example thickness of about 0.00048'' thick (e.g., about
0.0002''-0.002''). The middle film layer can be a high moisture
barrier polymer layer such as the GL films supplied by Toppan of
Japan. Typically, this polyester film can have an oxide or
metalized coating on the inside of the laminated structure. This
coating could have varying moisture transmission values depending
on the type and the amount of vacuum deposited oxides, or metals.
The third film layer, which can be on the outside of the completed
cell, can be a polyester layer that can act as a structural layer.
This structural layer of the five ply layer structure can be
orientated polyester (OPET) and have a thickness of about 0.002''
(e.g., about 0.0005''-0.010''), which can also be laminated to the
other layers by means of a urethane adhesive that is about 0.2 mil
thick, for example. This "structural layer" can be a DuPont
polyester orientated (OPET) film such as their Melinex brand, for
example. Another material that can be used is from Toyobo Co. Ltd.
of Japan, which is polyester based synthetic paper, which is
designated as white micro-voided orientated polyester (WMVOPET). In
some cases, for example where the cell by design has a higher
gassing rate and a short life cycle, it may be appropriate and
desirable to use a film with a higher transmission rate to allow
for a larger amount of gas to escape, so as to minimize cell
bulging. Another example would be an application that is in a hot
dry environment such as a desert or some special industrial
application. In such cases, it may be desirable to have a barrier
film with low transmission rates to prevent excessive moisture loss
from the batteries.
[0069] The use of a thicker substrate, by increasing any or all of
the polymer thicknesses, may have some advantages: These may
include one or both of the following: The cells process better on
printing press due to the thicker substrate being less temperature
sensitive; and The cell package is stiffer and stronger.
[0070] In addition to the above specifications, both the outside
and the inside layers could include the addition of a
print-receptive surface for the inks, metalized films and/or a very
thin metal foil or foils as a moisture barrier. These may include
one or more of the following: Laminated structures with metal
barriers (thin metal foil or a vacuum metalized layer) are likely
more expensive; Laminated structures with metal layers have the
possibility of causing internal shorts; and Laminated structures
that include a metal barrier could interfere with the electronics
of an application, such as the functionality of a RFID antenna, for
example.
[0071] The various substrates described herein can be comprised of
numerous variations of polymeric film, with or without a barrier
layer (including metal or other materials), and can utilize either
mono-layer or multi-layer films, such as polyesters or polyolefin.
Polyester is a good material to utilize because it provides
improved strength at the high temperature drying conditions, thus
permitting use of a thinner gauge film and is typically not easily
stretched when used on a multi-station printing press. If a very
long shelf life is desired, and/or the environmental conditions are
extreme, the multi-ply laminates could be modified to include a
metalized layer such as obtained by vacuum deposition of aluminum
in place of the oxide coating.
[0072] Alternately, a very thin aluminum foil could be laminated
within the structure of the film layer, or even in a different
position that would be of a lower cost and still allow the cell to
function for the desired lifetime.
[0073] In applications where only an extremely short life is
desired, the cell package could instead use a film layer of a low
cost polymer substrate such as polyester or polyolefin. It is
possible that the pressure sensitive adhesives for coupling and/or
sealing the various substrates together could be replaced with a
heat sealing system on the laminates. For example, a heat sealing
coating or the like could be used, with one such example material
being the Ovenable Lidding (OL) films made by Dupont and designated
as their OL series such as OL, OL2 or OL13.
[0074] For at least some embodiments, a water-based ink
electrochemical layer is printed as the cathode. Such a cathode
layer can include, for example, manganese dioxide (MnO2), carbon
(e.g., graphite), a polymer binder, and water. Other formulations
for the cathode layer can also be utilized with or without any of
these materials. If a cathode collector layer is used, the cathode
electrochemical layer will be printed on at least a portion of the
cathode current collector, which is printed or otherwise applied
first to the substrate. Still, the cathode current collector may or
may not form a portion of the cathode layer.
[0075] Regarding the anode, the anode layer could be applied by
printing a zinc ink onto the substrate or on top of a collector,
such as carbon. Where carbon is used, it could be printed in the
same station as the carbon collector used for the cathode and
electrical bridge. Alternatively, in an off-line operation, a
dry-film adhesive layer, possibly using a release liner, can be
applied to the zinc foil. The zinc foil can then be laminated to
the base substrate.
[0076] Optionally, printed over one or both the anode and cathode,
is a starch ink or similar material. The starch ink can act as an
electrolyte absorber to keep the electrodes "wet" after an aqueous
electrolyte solution is added to the cell. This starch ink could
also include the electrolyte salts and the water used for the cell
reaction. A paper layer over the anode and cathode could be used in
place of the printed starch. In at least one embodiment, the
construction of the printed starch layer with the addition of the
aqueous electrolyte could be replaced, for example, by a printable
viscous liquid (which could include a gel, or some other viscous
material) that effectively covers at least a portion, such as
substantially all, of each electrode. One such printable gel is
described in United States Patent Publication 2003/0165744A1,
published on Sep. 4, 2003, and incorporated herein by reference.
These viscous formulations could, for example, utilize the
electrolyte formulas and concentrations as discussed herein.
[0077] Optionally, for some embodiments, after the two electrodes
are in place, with or without the starch layer(s), an optional cell
"picture frame" can be added. This could be done using a number of
different methods. One method is to print this optional cell
picture frame with a dielectric ink and/or adhesive, for example.
Another method is to utilize a pressure sensitive adhesive or even
an optional polymer sheet or a laminated polymer sheet that
includes adhesive layers, that is stamped, die cut, laser cut or
similar methods to form the appropriate "pockets" (inner space or
spaces) to house materials of each unit cell as well as to expose
the electrical contacts to connect the device. It is contemplated
that the flexible battery can be formed with or without the frame.
For example, while the frame can offer one method for providing
inner space for the electrochemical cells, it is also contemplated
that the first and second substrates could be secured together to
provide the inner space for the electrochemical cells without the
use of a frame.
[0078] To ensure good sealing of the picture frame to the
substrates, and to provide good sealing of the contact feed-through
(providing an electrical pathway from the cell inside to the cell
exterior), a sealing or caulking adhesive could be printed over the
contact feed-through and the substrate, such as in the same pattern
as the cell frame, for example, prior to the frame being printed or
prior to the polymer sheets being inserted, for example. This
sealing or caulking material could be pressure sensitive, and/or
heat sensitive, or any other type of material that would facilitate
sealing to both surfaces.
[0079] After the dielectric picture frame is printed and dried
and/or cured, a heat sensitive sealing adhesive can be printed on
top of the frame to allow good sealing of the top substrate to the
cell frame. This cell picture frame could also comprise a polymer
film or a laminated film of about 0.015'' thick (range of about
0.003''-0.050'') that is pre-punched and then laminated in
registration to match the preprinted caulking adhesive layer
described above.
[0080] Zinc chloride (ZnCl2) can be chosen as the electrolyte, for
at least some embodiments, in the concentration range of about
18%-45% by weight, for example. In one example, about 27% may be
preferred. The electrolyte can be added, for example, to the open
cell. To facilitate processing on the line, this electrolyte, or a
different electrolyte, could be thickened with, for example, CMC at
about a level of about 0.6 wgt % (range of about 0.05%-1.0%).
[0081] Other useful electrolyte formulations, such as ammonium
chloride (NH4Cl), mixtures of zinc chloride (ZnCl2) and ammonium
chloride (NH4Cl), zinc acetate (Zn(C2H2O2)), zinc bromide (ZnBr2),
zinc fluoride (ZnF2), zinc tartrate (ZnC4H4O6.H2O), zinc
per-chlorate Zn(ClO4)2.6H2O), potassium hydroxide, sodium
hydroxide, or organics, for example, could also be used.
[0082] Zinc chloride may be the electrolyte of choice, providing
excellent electrical performance for ordinary environmental
conditions normally encountered. Likewise, any of the above
mentioned alternative electrolytes, among others, could be used in
concentrations (by weight), for example, within the range of about
18%-50%, with the range of about 25%-45% used for at least some
other embodiments. Such compositions could also provide acceptable
performance under ordinary environmental conditions. When zinc
acetate is used to achieve improved low temperature performance for
low temperature applications, the zinc acetate concentration in the
range of about 31-33, is often acceptable, although ranges of about
30-34, about 28-36, about 26-38, and even about 25-40, weight
percent, could also be utilized.
[0083] The use of electrolytes other than of zinc chloride can
provide improved cell/battery electrical performance under some
differing environmental conditions. For example, about 32% by
weight zinc acetate (F.P.--freezing point--about 28.degree. C.)
exhibits a lower freezing point than about 32% by weight zinc
chloride (F.P. about -23.degree. C.). Both of these solutions
exhibit a lower freezing point than of about 27% zinc chloride
(F.P. about -18.degree. C.). Other zinc acetate concentrations,
e.g. about 18-45 or about 25-35 weight percent, also exhibit
reduced freezing points. Alternatively, an alkaline electrolyte
such as Sodium hydroxide (NaOH) or potassium hydroxide (KOH) could
be used as an electrolyte to provide improved cell/battery
electrical performance under some differing environmental
conditions. The cell performance could be greatly enhanced due to
the much higher conductivity of the KOH electrolyte. For example, a
good working range of KOH would be concentrations (by weight)
within the range of about 23%-45%. Where an alkaline electrolyte is
used, it can be beneficial to utilize a suitable and chemically
compatible material for the top and/or bottom substrates of the
flexible battery, such as nylon, polyolefin, or the like.
[0084] Use of such electrolyte formulations as substitutes for zinc
chloride, or in various mixtures used in cells, can allow for
improved performance at low temperatures. For example, it has been
found that the use of an about 32% zinc acetate electrolyte
substantially improves low temperature (i.e. below about
-20.degree. C.) performance of a voltaic cell. This type of
electrochemical cell performance improvement at low temperature can
be utilized in the growing business of battery assisted RFID tags,
for example, and/or other transient (transportable) electrically
operated devices, such as smart active labels and temperature tags,
for example, which may be used in cold environments.
[0085] For example, many products that are shipped today, such as
food products pharmaceuticals, blood, etc, may require low
temperature storage and shipping conditions, or even low
temperature operation. To ensure safe shipment of such goods, these
items can be tracked with RFID tags, sensors, and/or displays.
These tags and/or labels might require electrochemical cells and/or
batteries to operate effectively at temperatures at, or even below,
-20.degree. C., such as at about -23.degree. C., about -27.degree.
C., or even at about -30.degree. C. or less.
[0086] The upper substrate of a cell package could utilize a
special laminated polymeric film. The upper layer is sealed around
the edges of the cell frame by means of a pressure sensitive
adhesive (PSA), and/or with the heat sensitive sealing adhesive
that was previously printed or just with the heat sealing layer of
both the upper and lower substrates, thus confining the internal
components within the cell frame.
[0087] The above-described constructions can be wet cell
constructions; however, using a similar cell construction, the
battery could be also be made into a reserve cell construction,
which has the benefit of providing extended shelf life prior to the
application of a liquid. The printable, flexible, zinc chloride
thin cell is made environmentally friendly.
[0088] The devices for which this technology can be used are
extensive. Devices that utilize relatively low power or a limited
life of one to three years, and possibly longer, could function
utilizing a thin cell/battery of the type described herein. The
cell, as explained in the above paragraphs and below, can often be
inexpensively mass-produced so that it can be used in a disposable
product, for example. The low cost allows for applications that
previously were not cost effective, and could now be commercially
feasible.
[0089] The electrochemical cell/battery according to the
application might have one or more of the following advantages:
Flat, and of relatively uniform thickness, where the edges are
thinner than the thickness at the center; Relatively thin; Flat,
and of relatively uniform thickness, where the edges are of about
the same thickness as the center; Flexible; Many geometric shapes
are possible; Sealed container; Simple construction; Designed for
high speed and high volume production; Low cost; Reliable
performance at many temperatures; Good low temperature performance;
Disposable and environmentally friendly; Both cell/battery contacts
provided on opposite surfaces, or even the same surface; Both
Cell/battery contacts can be provided at many locations on the
battery exterior; Ease of assembly into an application; and Capable
of being easily integrated in a continuous process at the same time
that the electronic application is being made.
[0090] The above provides a general description of various cell
constructions according to some embodiments of this application,
and further details utilizing drawings follow below. Cell and
battery production processes for cell manufacturing, printing
and/or assembly also will be described as well.
[0091] In one example, such as where relatively high speed, high
output manufacturing is contemplated, such as 50 linear feet per
minute or another relatively high speed, multiple webs can be used.
It is to be understood that the multiple webs can be generally
continuous, and can be utilized with known web manufacturing
equipment. A first web can be relatively thin, such as
.about.0.001''-0.010'' and preferably about 0.002-0.006'', flexible
base substrate including a multi-ply laminated structure or single
ply material. In one example, the multi-ply structure can include
five layers. Alternatively, the single ply material can include
various materials, such as Kapton, polyolifins or polyester.
Additionally, if the 0.001'' layer is too thin to handle
efficiently on the printing press and/or on other operations, then
a thicker throw away support layer with a low tact pressure
sensitive adhesive layer could be laminated to the thin substrate
layer. Also, this 0.001'' substrate layer could be made from more
than one ply with a very thin oxide layer which performs as a water
barrier on the inside surfaces. After the printing and assembly
operations are completed, then the throw away support layer could
be removed.
[0092] A second web could be a relatively thicker laminated
structure including a PVC or Polyester film that is about
0.003-0.030'' thick, and preferably about 0.006-0.015'' thick. The
second web can have a layer of pressure sensitive adhesive (without
the release liner) at about 1-5 mils thick on one or both sides.
After this laminated structure of the second web is completed, it
can be applied to the first web. In addition or alternatively, the
second web can be pattern cut using any type of mechanical means to
allow for cavities for the cells active materials as well as an
optional cavity for the cell/battery contacts. A third web can be a
relatively thin laminated structure the same and/or similar to the
first web. The completed three web structure may have a pressure
sensitive adhesive on either side to allow the individual device
assembly to be applied as a label. The cell/battery may be of the
thin cell type, such as described in co-pending U.S. application
Ser. No. 11/110,202 filed on Apr. 20, 2005, Ser. No. 11/379,816
filed on Apr. 24, 2006, Ser. No. 12/809,844 filed on Jun. 21, 2010,
Ser. No. 13/075,620 filed on Mar. 30, 2011, Ser. No. 13/625,366
filed on Sep. 24, 2012, and Ser. No. 13/899,291 filed on May 21,
2013, as well as issued U.S. Pat. Nos. 8,029,927, 8,268,475,
8,441,411, 8,574,745, all of which are incorporated herein by
reference.
[0093] Depending on the cell construction, the cell application,
and/or the cell environment, it may be advantageous to have
different barrier properties for the substrate. Due to the wide
range of available vapor transmission rates available, the barrier
layer can be chosen for each specific application and construction,
as desired. In some cases, for example where the cell by design has
a higher gassing rate and/or a short life, it may be appropriate
and desirable to use a film with a higher transmission rate to
allow for a larger amount of gas to escape, so as to minimize cell
bulging. The barrier layer is designed to minimize water loss but
still allow generated gasses of normal electrochemical reactions to
escape thus reducing the chances of the thin cell to bulge. Another
example would be an application that has a long shelf life or is in
a hot dry environment such as a desert. In such cases, it may be
desirable to have a barrier film with low transmission rates to
prevent excessive moisture loss from the cell. At least one of the
first and second substrate layers can comprise a plurality of
laminated layers including an oxide barrier layer having a gas
transmission rate that permits gas to escape through said plurality
of laminated layers of said first or second substrate layer, but
still reduces (e.g., minimizes) the escape of water vapor. In
addition or alternatively, the oxide coated moisture barrier layer
can have a moisture vapor transmission rate that permits moisture
vapor to escape through said plurality of laminated layers of the
covering layer to an external environment, and may not include a
metal foil layer. It is understood that because the oxide barrier
layer can be designed to provide a desired gas transmission rate
and/or moisture vapor transmission rate, the oxide barrier layer
non-hermetically seals the battery against gas and/or moisture.
[0094] Various embodiments of example constructions of the
laminated film substrates can be utilized. The lower and upper
laminated film layers can, in most cases and for most applications,
be of the same materials. In at least one embodiment, these film
layers can be comprised of a five-ply laminate film, for example.
In another example, the laminated film substrates can have four
layers. The top layer placed on the inside of the cell has an
example thickness of about 0.48 mil thick (about 0.2-5.0 mil) and
is a high moisture barrier polymer layer film that provides a
flexible, heat-sealable web that has the following barrier
properties: oxygen transmission rate of less than about 0.045 cubic
centimeters per 100 square inches per 24 hours at about 3.degree.
C. and 70% relative humidity; and MVTR of between about 0.006-0.300
grams water per 100 square inches per 24 hours at about 4.degree.
C. and 90% relative humidity.
[0095] Typically, this polyester film has an oxide or metalized
coating on the inside of the laminated structure. These polymer
(polyester)-based barrier films, which can have varying moisture
transmission values depending on the type and the amount of vacuum
deposited oxides, or metals, and can be laminated to the bottom
polyester layer and which acts as a structural layer with a
Urethane adhesive. The inside layer of these substrates can include
a heat sealing layer. Another alternative high moisture barrier
could be a flexible, heat-sealable web that has the following
barrier properties: oxygen transmission rate of less than about
0.045 cubic centimeters per 100 square inches per 24 hours at about
73 F and 50% relative humidity; and MVTR of less than about 0.30
grams water per 100 square inches per 24 hours at about 100 F and
90% relative humidity.
[0096] In another example, an outside layer (or structural layer)
of a multi-layer structure can include an about 2.0 mil (about
0.5-10.0 mil) layer of orientated polyester (OPET), which is
laminated to the other layers by means of an urethane adhesive that
is about 0.1 mil thick, for example. This "structural layer" can be
a polyester orientated (OPET) film, or polyester based synthetic
paper, which is designated as a white micro-voided orientated
polyester (WMVOPET).
[0097] The use of a thicker substrate, by increasing any or all of
the polymer thicknesses, may have some advantages: These may
include one or both of the following: The cells process better on
printing press due to the thicker substrate being less temperature
sensitive; and The cell package is stiffer and stronger.
[0098] In addition to the above specifications, either or both the
outside and the inside layers could include the addition of a
print-receptive surface for the required inks. The inside layer is
used for the functional inks (such as the collector and/or
electrochemical layers) while the outside layer can be used for
graphical inks, if desired. Flat cell constructions having a sealed
system might utilize a laminated structure that includes metallized
films and/or a very thin metal foil or foils as a moisture barrier.
Although such structures using a metal layer might have better
moisture barrier properties than the constructions used for some of
the above described embodiments, it might also have some
disadvantages. These may include one or more of the following:
Laminated structures with metal barriers (thin metal foil or a
vacuum metallized layer) are likely more expensive; Laminated
structures with metal layers have the possibility of causing
internal shorts; and Laminated structures that include a metal
barrier could interfere with the electronics of an application,
such as the functionality of a RFID antenna, for example.
[0099] The film substrates can be comprised of numerous variations
of polymeric film, with or without a barrier layer (including metal
or other materials), and can utilize either mono-layer or
multi-layer films, such as polyesters or polyolefin. Polyester is a
good material to utilize because it provides improved strength
permitting use of a thinner gauge film and is typically not easily
stretched when used on a multi-station printing press. Vinyl,
cellophane, and even paper can also be used as the film layers or
as one or more of the layers in the laminated constructions. If a
very long shelf life is desired, and/or the environmental
conditions are extreme, the multi-ply laminate polymer could be
modified to include a metallized layer such as obtained by vacuum
deposition of aluminum in place of the oxide coating.
[0100] Alternately, a very thin aluminum foil could be laminated
within the structure of the film layer, such as for layer, or in a
different position. Such a modification could reduce already low
water loss to practically nil. On the other hand, if the
application is for a relatively short shelf life and/or a short
operating life, a more expensive barrier layer could be replaced
with a less efficient one which would be of a lower cost and still
allow the cell to function for the required lifetime.
[0101] In applications where only an extremely short life is
necessary, the cell package could instead use a film layer of a low
cost polymer substrate such as polyester or polyolefin. It is
possible that the pressure sensitive adhesive sealing system for
adhering the frame to the top substrate and lower substrate could
be replaced with a heat sealing system on the laminates.
[0102] In a simplified construction of the upper and/or lower
laminate substrates, laminate barrier layers could be laminated
together with urethane adhesive layer, for example. Alternatively,
a substrate could be provided with an additional layer that is a
barrier coating on barrier layer. In addition, layers could be
laminated together with urethane adhesive layer.
[0103] Alternatively, an example seven-layer laminate substrate
could be used for the substrate of the cell. A heat sealing layer
can be laminated to the previous structure using an adhesive layer.
The approximate 50-gauge heat seal layer can be a composite layer
that also includes a heat sealing coating such as amorphous
polyester (APET or PETG), semi crystalline polyester (CPET),
polyvinyl chloride (PVC), or a polyolefin polymer etc. on polymer
film such as polyester. This would thus make the top substrate
and/or the bottom substrate of the previously described cell into a
7-ply construction. Depending on the thicknesses of the various
layers, any of these structures (three-ply, four-ply, and seven-ply
laminates, respectively), the total thickness of these laminates
could be about 0.003'' with a range of about 0.001-0.015'' for at
least some embodiments. Alternatively, different substrate
constructions could be utilized as well, including more or less
layers, depending on the desired applications and qualities.
[0104] The various conductive inks described herein could be based
on many types of conductive materials such as carbon, silver, gold,
nickel, silver coated copper, copper, silver chloride, zinc and/or
mixtures of these. For example, one such material that shows useful
properties in terms of conductivity and flexibility is silver ink.
Furthermore, various circuits, electrical pathways, antennas, etc.
that might be part of the printed circuitry can be made by etching
aluminum, copper or similar type metallic foils that are laminated
on a polymer, such as a polyester substrate. This could be done
with many types (sizes and frequencies) of pathways and/or antennas
whether they are etched or printed.
[0105] The thin printed flexible electrochemical cell includes a
printed cathode deposited on a printed cathode collector (e.g., a
highly conductive carbon cathode collector) with a printed or foil
strip anode placed adjacent to the cathode. Electrochemical
cells/batteries of this type are described in co-pending U.S.
application Ser. No. 11/110,202 filed on Apr. 20, 2005, Ser. No.
11/379,816 filed on Apr. 24, 2006, Ser. No. 12/809,844 filed on
Jun. 21, 2010, Ser. No. 13/075,620 filed on Mar. 30, 2011, Ser. No.
13/625,366 filed on Sep. 24, 2012, and Ser. No. 13/899,291 filed on
May 21, 2013, as well as issued U.S. Pat. Nos. 8,029,927,
8,268,475, 8,441,411, 8,574,745, the disclosures of which is
incorporated herein by reference. The electrochemical cell/battery
can also include a viscous or gelled electrolyte that is dispensed
onto a separator that covers all or part of the anode and cathode,
and a top laminate can then be sealed onto the picture frame. This
type of electrochemical cell was designed to be easily made by
printing (e.g., through use of a printing press), and allows, for
example, for the cell/battery to be directly integrated with an
electronic application.
[0106] As shown in FIGS. 5-8, the flexible batteries 2000, 3000 for
generating an electrical current are shown in various detail views.
Though not explicitly stated, the flexible battery can include any
of the battery structure or methodology described herein. The
flexible battery, including one or more cells, is printed on a
single side of a single substrate (the top substrates are not shown
for clarity). It is understood that various portions of the battery
could be printed on opposite sides of a substrate, although it can
be more cost effective to print the battery on a single side of a
substrate. Additionally, though the battery can be formed using a
printing process for each element, some or all of the elements can
be provided via a non-printed process, such as laminates,
adhesives, strips of material, etc.
[0107] The battery includes a thin printed flexible electrochemical
cell, which may include an optional sealed "picture frame"
structure, that includes a printed cathode deposited on a printed
cathode collector (e.g., a highly conductive carbon cathode
collector) with a printed or foil strip anode placed adjacent to
the cathode. The electrochemical cell/battery also includes a
viscous or gelled electrolyte that is dispensed onto a separator
that covers all or part of the anode and cathode, and a top
laminate can then be sealed onto the picture frame. This type of
electrochemical cell was designed to be easily made by printing
(e.g., through use of a printing press), and allows, for example,
for the cell/battery to be directly integrated with an electronic
application.
[0108] Various other substrates can be utilized as a spacer frame.
For example, the third substrate can be composed of various
materials, such as PVC or PET film at about 0.0005''-0.030'' thick
and preferably at about 0-0.005''-0.015'' that is sandwiched
between (i.e., interposed between) two layers of a pressure
sensitive adhesive (PSA) that is about 0.003'' thick
(0.001''-0.005'') and includes a release liner. Additionally the
spacer could be printed with a cured dielectric or some other
curing and/or drying method. This material, such as Acheson
Colloid's PM030, can also be a pressure sensitive adhesive, thus
possibly eliminating the need to print an extra layer of
adhesive.
[0109] To make the manufacturing process of a cell/battery more
efficient and/or achieve greater economies of scale, the
cell/battery can be manufactured using a generally continuous web
in a reel-to-reel printing process to provide production at high
speeds and low cost. An example manufacturing procedure is
described in the following paragraphs. In this example procedure,
the cell/battery proceeds through numerous stations that are
compatible with a high-speed printing press running a roll-to-roll
setup. Though not further described herein, the processing and
assembly could be integrated with the manufacture of the flexible
battery or elements thereof to be powered by the battery, such as
with the electrical component, etc.
[0110] According to available printing presses, the cells could be
made with one pass, or multiple passes, on a given press, for
example. As an example, two rows of individual cells on the web;
however, the number of rows is limited only to the size of the unit
cells and the maximum web width that the press can process. Because
there may be numerous steps, thereby likely utilizing a long and
complicated press, some of these steps, as well as some of the
materials, could be modified and/or multiple passes of a press or
multiple presses could be used. Moreover, any or all of the
printing steps can be performed by screen printing, such as by flat
bed screens or even rotary screen stations. Additionally, one
skilled in the art would realize that one printing press with more
than five stations could be difficult to find and or to operate,
and thus the following discussion of the process could occur on one
or more presses or even multiple passes through one press.
[0111] During manufacturing, various optional operations may or may
not occur. For example, the optional operations could include one
or both of heat stabilization of the web and graphics printing
(which could include logos, contact polarities, printing codes and
the addition of registration marks on the outside surface of web).
If these optional printing operations occur on the web, then the
web can be turned over and the functional inks can be printed on
the inside surface, (i.e., the heat seal layer).
[0112] One skilled in the art would realize that there are many
methods, materials, and sequences of operations that could be used,
and that more or less, similar or different, numbers of stations
could also be utilized. Various designs and methods of manufacture
of a flat cell and batteries are described in co-pending U.S.
application Ser. No. 11/110,202 filed on Apr. 20, 2005, Ser. No.
11/379,816 filed on Apr. 24, 2006, Ser. No. 12/809,844 filed on
Jun. 21, 2010, Ser. No. 13/075,620 filed on Mar. 30, 2011, Ser. No.
13/625,366 filed on Sep. 24, 2012, and Ser. No. 13/899,291 filed on
May 21, 2013, as well as issued U.S. Pat. Nos. 8,029,927,
8,268,475, 8,441,411, 8,574,745, all of which are incorporated
herein by reference.
[0113] Generally, each of the electrochemical cells described
herein can provide about 1.5 volts. However, a number of the
electrochemical cells can be electrically coupled together if
higher voltages and/or high capacities are desired. For example, a
3 volt battery is obtained by connecting two 1.5 volt unit cells in
series, although other voltages and/or currents can be obtained by
using unit cells with different voltages and/or by combining
different numbers of cells together either in series and/or in
parallel. Different electrochemical systems could be customized for
the different battery configurations. Preferably, if different
cells are used to obtain higher voltages all of the cells in each
battery should be of the same electrochemical system. Thus,
applications using greater voltages can connect unit cells in
series, whereas applications requiring greater currents and/or
capacities, unit cells can be connected in parallel, and
applications using both can utilize various groups of cells
connected in series further connected in parallel. Thus, a variety
of applications that use different voltages and currents can be
supported using a variety of unit cell and/or battery
configuration.
[0114] Additionally, it is understood that the new cells described
herein can have a generally non-rectilinear geometry, and the
theoretical resistance can be similarly determined by dividing the
collector height by the narrowest width of the collector area.
However, where a generally non-rectilinear geometry is used, the
height and width can be determined by an effective height and an
effective width, respectively. For example, the effective height or
width can be an average height or width, or other mathematically
adjusted height and width that can approximate the height and width
measurements of a generally rectilinear geometry.
[0115] Thin printed flexible batteries can have many potential
applications, which can include one or more of the following
generally categories as examples: RFID assemblies; advertising and
promotion; toys, novelties, books, greeting cards, and games;
Inventory tracking and control such as (smart RFID tags); security
tags; condition indicators such as temperature, humidity, etc.;
skin patches that apply iontophoresis or other electrical function
for the purpose of drug delivery, wound care, pain management
and/or cosmetics; and Healthcare products such as smart diapers,
incontinence products, electronics to log and wirelessly transmit
and/or receive health data (such as body temperature), etc.
[0116] The invention has been described with reference to the
example embodiments described above. Modifications and alterations
will occur to others upon a reading and understanding of this
specification. Examples embodiments incorporating one or more
aspects of the invention are intended to include all such
modifications and alterations insofar as they come within the scope
of the appended claims.
* * * * *